Crystal structure of 1,2-vinylenbis(triphenylphosphonium) tetrabromocuprate(II), [Ph3P-CH=CH-PPh3][CuBr4]

Abstract

C 3 8H 3 2Br 4 P2Pb, monoclinic, C12/cl (No. 15), a = 10.913(2) Ä, b = 17.618(4)Ä,c = 19.848(4)Ä,β = 99.97(3)°, V= 3758.5Ä 3 , Ζ = 4, /fgt(F) = 0.043, wR Kf (F 2) = 0.096, T= 293 K. Source of material PbBr 2 and [Ph 3 P-CH=CH-PPh 3 ][Br 2 ] were both dissolved in aqueous HBr, the solutions were mixed and water was slowly evaporated. After several hours a fine crystalline yellow powder precipitated. For the preparation of single crystals 1.5 g of this product and 5 ml H2O were filled into a glass ampoule which was sealed and heated to 45 3 K. The ampoule was cooled with a rate of 10 K/min to ambient temperature. Discussion Lead atom is coordinated by four bromide ligands, in form of a trigonal ψ-bipyramide with one equatorial position occupied by the s 2-pair. The axial Pb-Br bond lengths are 2.99 Ä, the equatorial lengths 2.70 Ä, Br(ax)-Pb-Br(eq) angles are in the range 95.53° to 99.42°, the bond angle between the two axial Br-atoms is 159.0°. The data agree with those observed in comparable bromoplumbates(II) [1]. The distorted ψ-bipyramide was so far not observed in the structure of lead bromides with organic cat-ions. Cations and anions form waved layers, which are stacked along the α-axis in the order A,A,A. Bond distances and bond angles in the cation agree well with the data of Stang and Zhdankin [2], The compound was investigated with a differential scanning calorimeter. Between 153 Κ and 423 Κ no phase transition was detected.

Crystal Structure and Magnetism of a Well Isolated 2D-Quantum Heisenberg Antiferromagnet, (Quinolinium)2CuBr4·2H2O, and Its Anhydrous Form

“…There are two unique Cu-Br bonds within each CuBr 4 2ion, the other bromide ions being generated by the C 2 axis through the Cu(II) ion. The Cu-Br bond lengths in 1 (2.3469(4) and 2.4118(4) A ˚) are similar to those seen in other compounds with smaller mean trans angles, such as (3-ethylpyridinium) 2 CuBr 4 21 (2.373 and 2.388 A ˚, mta = 130.1°) and (1,2-vinylene(triphenylphosphonium)) 2 CuBr 4 22 (2.372 and 2.426 A ˚, mta = 124.8°). Waters of hydration are located within layers of CuBr 4 2distorted tetrahedra (Figure 3).…”